Device for sorting comestibles



Dec. 30, 1952 J R 2,623,635

DEVICE FOR SORTING COMESTIBLES Filed Oct. 22, 1948 13 Sheets-Sheet 1 grwwrvkw DELBERT (I WFIRD Dec. 30, 1952 D. J. WARD 2,623,635

DEVICE FOR SORTING COMESTIBLES Filed Oct. 22, 1948 13 Sheets-Sheet 2 Dec. 30, 1952 J WARD DEVICE FOR SORTING COMESTIBLES 13 Sheets-Sheet 3 Filed Oct. 22, 1948 6-. 6. 71- DELBERT (I WHRD Dec. 30, 1952 J WARD 2,623,635

DEVICE FOR SORTING COMESTIBLES Filed Oct. 22, 1948 13 Sheets-Sheet 4 9 awe/whom 30, 1952 D. J. WARD 2,623,635

DEVICE FOR SORTING COMESTIBLES Filed Oct. 22, 1948 13 Sheets-Sheet 5 aw 1a 40,4 DELBERT J WFIRD waw Dec. 30, 1952 Filed Oct. 22, 1948 i: dm hlp 262 D. J. WARD DEVICE FOR SORTING COMESTIBLES l3 Sheets-Sheet 6 I V //1 w I i 20 7 a Era-.15: DELBERT J. WHRD Dec. 30, 1952 J, A D 2,523,635

DEVICE FOR SORTING COMESTIBLEIS Filed Oct. 22. 1948 13 Sheets-Sheet 7 FIG-.15.

3mm .DfLBtf/iT J Warm FIE-.18. W

Dec. 30, 1952 D. J. WARD 2,623,635

' DEVICE FOR SORTING COMESTIBLES Filed Oct. 22, 1948 15 Sheets-Sheet 8 1.. ll/111110 9 II-.//IIIIIIIIII%IIIIII v M v Dec. ,1 D. J. WARD 2,623,635

DEVICE FOR SORTING COMESTIBLES Filed Oct. 22, 1948 15 Sheets-Sheet 9 lllllllllllll D 1952 D. J. WARD 2,623,635

DEVICE FOR SORTING COMESTIBLES Filed Oct. 22, 1948 is Sheets-Sheet 1o INVENTOR. DEL BERT J Wfl/m BY fi A77'OR/YEYS Dec. 30, 1952 D. J. WARD DEVICE FOR SORTING COMESTIBLES l3 Sheets-Sheet 11 Filed Oct. 22, 1948 JNVENTOR. DZBRT d. W/IRD BY wrfizK ATTORNEYS SMQ wutulukik Patented Dec. 30, 1952 UNITED STATES PATENT OFFICE 16 Claims.

The present invention relates to an improved device for sorting or grading of comestibles such as dates, fruits, nuts and the like, according to the internal moisture content of the comestible, the device shown and claimed herein being specifically applicable to the sorting and grading of dates.

In accordance with the present invention, dates are fed individually through a high frequency measuring circuit and sorted and graded according to the relative moisture content, the moisture content of a particular date being effective to influence appreciably in varying degrees the high frequency current or voltage in a high frequency measuring circuit. While certain principles of the present invention may be applied in high frequency measuring circuits in which a date passes through only one electrode arrangement, preferably, in accordance with the present invention, a date is successively passed through a pl-urality of electrode arrangements and the associated apparatus is opera-ted in accordance with a plurality of determinations obtained in different electrode structures oriented differently with respect to the same date for increased accuracy and dependability.

In the distribution of dates, it is very desirable to know the moisture content of each individual date whereby the dates may suitably be processed and oifered to the public in the best possible condition. In the event that the moisture content of the date is too low, moisture may be added thereto in accordance with well known processes and, conversely, if the moisture content of the date is too high, it may be dehydrated in varying degrees. For ease and efficiency in handling, it is desirable that batches of dates of the same moisture content, of course, be treated in the same way. In order to achieve this condition, it is initially necessary to sort or grade dates according to their moisture content. The present apparatus serves this purpose, namely, of grading and sorting dates in accordance with its moisture content.

An object of the present invention is to provide an improved comestible sorting and grading apparatus operated. in accordance with the moisture content of the comestible, the apparatus being characterized byits automatic operation and accuracy with which the desired results are obtained.

Yet another object of the present invention is to provide an improved comestible sorting andv grading apparatus which, in accordance with important features of the present invention, em-

bodies a novel electrode arrangement wherein a comestible is subjected to three different determinations in its passage through the apparatus.

Still another object of the present invention is to provide an improved sorting and grading apparatus characterized by the accuracy with which the individual comestibles are sorted or graded.

Yet another object of the present invention is to provide an improved sorting and grading apparatus which includes as its feature determination of the moisture content of comestibles using high frequency currents.

Yet another object of the present invention is to provide an improved comestible sorting and grading apparatus which incorporates novel high frequency control apparatus for achieving the above indicated results.

Yet another object of the present invention is to provide an improved high frequency comestiole sorting and grading apparatus incorporating as features thereof a novel electrode arrangement within which moisture determinations are made and averaged as the comestible passes therethrough.

Still another object of the present invention is to provide an improved sorting and grading apparatus in which moisture content of comestibles may be determined substantially independently of electrode contact resistance and without piercing the comestible.

Yet another object of the present invention is to provide an improved high frequency sorting or grading apparatus characterized by the fact that it incorporates a novel compensating circuit arranged to make moisture determinations substantially independently of the voltage of the high frequency source or variations in such voltage.

Still a further object of the present invention is to provide an improved electrical responsive sorting and grading apparatus characterized by the fact that the apparatus is ultimately actuated in accordance with a plurality of measurements of moisture content taken in different directions through the comestible.

Yet a further object of the present invention is to provide an improved electrical responsive sorting and grading apparatus which incorporates a compensatory circuit arranged to render moisture determinations substantially independently of voltage of its high frequency source and characterized further by the fact that the apparatus is ultimately operated in accordance with the average a plurality of difierent determinations made on the same comestible.

Still a further object of the present invention is to provide an improved sorting and grading apparatus in which the structural elements thereof are arranged in a novel manner for convenience of assembly, servicing and maintenance.

Yet a further object of the present invention is to provide an improved sorting and grading apparatus characterized by its simplicity and compactness.

Still a further object of the present invention is to providean improved comestible measuring and sorting apparatus characterized by the fact that it is operated in accordance with the average value of a plurality of impedance measurements made thereon.

Yet a. further object of the present invention is to provide an improved date sorting and grading apparatus through which dates of widely varying moisture content may be run and automatically separated or stored in accordance with diiferent degrees of moisture content.

Another object of the present invention i .to provide an improved electrode system arranged for use in a high frequency circuitfor determining electrical characteristics of comestibles passing therethrough, a subsidiary feature being that capacity changes resulting from such electrodes moving in accordance with varying-sized comestibles are substantially eliminated so that the ultimate determination is substantially independent of the size of the comestible.

Another object of the present invention is to provide an improved fully automatic multiple high frequency sorting or grading apparatus arranged so that a single radio frequency power supply furnishes the power simultaneously for a plurality of measuring systems.

The features of the present invention which are believed to be novel are set forth with particularity in the appended claims. This invention itself, both as to its organization and manner of operation, together with further objects and advantages thereof, may be best understood by reference to the following description taken in connection with the accompanying drawings in which:

Figure 1 is a view in front elevation of a portion of the apparatus embodying the present invention.

Figure 2 is a View in side elevation thereof taken substantially on the line 22 of Figure, 1.

Figures 3, 4 and 5 show in greater detail some of the apparatusshown in Figure 2.

Figure Bis a sectional view taken substantially as indicated on the line 65 of Figure 2.

Figure 7 is a top plan view taken as indicated by the line T! of Figure 1.

Figure 8 is a perspective view of a portion of the apparatus shown in Figure l with some of the removable elements omitted to show the structural figures.

Figure 9 is a sectional view taken substantially on the line 99 of Figure 8.

Figures 10, 11 and 12 are sectional views taken substantially on corresponding lines in Figure 15.

Figure 13 is a perspective view of the plug-in electrode structure shown in Figure'9.

Figure'14 is a perspective view or the electrode fingers in each one of the three electrode arrangements shown in Figures 13 and 15.

Figure 15 is a longitudinal sectional view taken substantially as indicated by the line l5l5 in Figure 13.

Figure 16 is a view taken substantially in the direction indicated by the line l6! 6 ofFigure 9.

Figure 1'7 is a view taken substantially as indicated by the line HI'I in Figure 16.

Figure 18 is a sectional view taken substantially on the lines l8l 8 in Figure 9.

Figure 19 is a sectional View taken substantially on the line l9-l 9 of Figure 16.

Figure 20 is a view taken substantially in the direction indicated by the lines 2020 in Figure 16.

Figure 21 is a sectional view taken substantially on the line 2 l-2l of Figure 23.

Figure 22 is a view taken substantially in the direction indicated by the lines 2Z22 in Figure 19.

Figure 23 is a View taken substantially in the direction indicated by the lines 23-23 in Figure 20.

Figure 24 is a view taken substantially as indicated by the lines 24-44 in Figures 16 and 25.

Figure 25 is a view taken substantially in the direction indicated by thelines .25-25 in Figure'Z.

Figure26 is a perspective view of the apparatus shown in Figure'24.

Figure '2'? is a view taken substantially in the direction indicated by the line 2l-21 in Figure 16.

Figure 28 is .an electric circuit diagram for illustrating some of the principles used in the operation of my electric apparatus embodying the features of the present invention, shown in greater detail in Figure'29.

Figure 29 is an electric circuit diagram of apparatus embodying the present invention.

Figure 30 shows another arrangement of electric apparatus whereby additional features of the present invention may be practiced.

Figure 31 is an electric circuit diagram for'illustrating some of .theprinciples used in the :operation of the apparatus shown in Figure 30.

Figure 32 shows another arrangement of apparatus for practicing still additional features. of the present invention.

Figures 33 and 34 are vectorial-circuit diagram representations useful in explaining operation of the apparatus shown in Figure 30.

Figure 35 illustrates the manner in which the output terminal of the high frequency voltage source is connected to four measuring channels, each of which comprises three electrode structures.

In. accordance with the present invention. dates are fed in re ulated amounts from achute 15 (Figures land '2) onto ahorizontally extending endless belt H which is continuously moved by the motor driven chain l2 inthe direction indi atedby the arrow 13 in Figures 1 and 7 to positions adjacent to the stationary angularly positioned deflecting members 15 and [6, the first deflecting member 15 extending over approximately one-half the width of the endless belt H to thereby deflect approximately one-half of the dates carried on belt ll onto the vibratory aligned chute or pan l'l, while the other deflecting member It extends the full width of the belt H to deflect the remaining dates on belt H into the other vibratory aligning pan l8.

The vibratory pans 1?, i3. best shown in Figures and 5, are mounted on individual me chanical vibrating units HA, IBA respectively.

which in turn are resiliently mounted through corresponding springs llB, I813 on the stationary support 22. These pans l1, IS, with the dates thus loaded therein, are vibrated to causesubstantially one-half of the dates in such pans to travel in single file, under the action of gravity forces, down the integrally formed corresponding channels or chute members HE, HF, IBE, IBF from where they may drop into the aligned spaced vertical tubes 25A, 26A, 21A and 28A respectively.

Thus, the date distributing mechanism described hereinabove serves to divide and cause one-fourth of the dates each to flow into the corresponding aligned tubes 25A, 26A, 21A and 28A and to pass such dates in single file to an individual independent measuring electrode system incorporated in the detachable housings 25, 26, 21 and 28.

In the event that the dates become crowded in the guide channel or chute members I 1E, l'lF, 18E and BF, so that they do not follow in single file, the ends of such channels, being tubular and disposed adjacent the stationarily mounted deflecting trays 23 and 24, cause the excess dates, not passable through such tubular portion, to contact the respective trays 23, 24 and slide therefrom under the influence of gravity onto the continuously moving horizontally disposed endless belt 29 which is driven by the same motoroperated chain l 2, through shaft l 23 (Figure 7), to move the dates in the direction indicated by the arrow as so as to allow them to fall into the discharge chute 3|.

The units 25, 2t, 2! and 28 are each exactly the same so that a description of unit 26 suffices to describe the other units 25, 2'1 and 28.

The unit 25 includes an electrode system best seen in Figures 9-15. Briefly, such electrode system incorporates three diiferently oriented condensers 26B, 25C and 25D through which dates are fed successively, in that order, in single file, after which they pass through the aligned guide tubes 25 and 36 respectively in units 26 and All.

The unit 4 3 underlies the unit 25 and its construction is typical of the other units 39, A! and 42 (Figure l) which underlie the units 25, 2'! and. 28. A description of device 4E! serves, therefore, as a suflicient description of devices 39, M and 42. A date passing through unit 26 continues in its vertical downward motion through the aligned tube 49A in unit 49 in the event that such date has a moisture content less than a predetermined moisture content.

than such predetermined moisture content, the date is automatically delivered to one of the three chutes 49B, 49C or 49D (Figure 26), depending upon the degree to which its moisture differs from such predetermined amount.

Thus, a date passing from unit either through the central tube 48A or down through chute 69B, 48C or 46D. In the latter three cases, the date is deflected by the corresponding solenoid actuated deflector plates 4013B. ECG and AilDD (Figure 16) and passes through either chute 48B, 40C or 40D into a corresponding receptacle or onto an endless belt (not shown). These deflector plates 4213B, 4 9cc, and WD'D are operated, as described more fully hereinafter, in accordance with the moisture content of the date. The deflector plates 4'JBB, MlCC, and MDD are each actuated by a similar mechanism so that a description of the solenoid actuated mechanism associated with the deflector plate 480C, shown in detail in Figures 19, 20, 21, 22, and 23, suffices to describe the similar mechanism associated with the other deflector plates.

In the event that the date has a moisture content greater 26 may pass Referring to the previously mentioned figures, the deflector plate 4000 is attached to the core member 60 associated with the solenoid 6|, the core member 60 being moved in the direction indicated by the arrow 62 in Figures 21 and 22 to produce rotative movement of the deflector plate 400C in the direction indicated by the arrow 63. Such rotative movement of the deflector plate 4000 is about the axis of the cylindrical core member 60. Normally, when the solenoid 61 is de-energized, the deflector plate 46CC assumes the position shown in Figures 20-23 inclusive, the deflector plate being urged in the position shown by the coil tension spring 64 having one of its ends aflixed to the deflector plate 400C and the other one of its ends attached to the bracket member 65 mounted stationarily with respect to the casing 66 of the solenoid 6 I.

In order to produce rotative movement of the deflector plate MSCC upon energization of the solenoid 6 I, there are provided three balls 61, 68,

69, equally spaced on a circle, the balls being disposed between re-entrant or depressed portions of the solenoid housing 66 and between the correspondingly spaced depressed cam portions in the cam plate -68 which is attached to the core member 60 for movement therewith, it being noted that the core member 60, cam plate 68, and deflector plate 46CC are thus mounted as a unit.

Thus, when the core member 68 moves in the direction indicated by the arrow 62 in Figure 21, when the solenoid S! is energized, the balls 61, 68, and 59, cooperatin with the depressed portions in the casing 65 and cam plate 68, cause the deflector plate 406C to rotate against the action of the tension spring 64. Such rotative movement of the deflector plate 4500 continues until the upper end thereof, in Figure 19, is disposed underneath the exit end of the tube 36 to thereby block the flow of dates from tube 36 into the central tube 48 and to thereby cause the dates to be deflected into the chute 48C.

The particular circuit arrangement whereby the solenoid BI is energized is described in detail hereinafter, as is also the circuit associated for energizing the solenoid associated with the other deflector plates 4033 and DD. The solenoid casing 66 is stationarily mounted with respect to the stationary bracket member 10 on the unit The unit 42, itself. may be supported on the upper L or T-shaped guide members73, 13 (Figure 8) within which they are releasably and firmly held by a pair of bow-leaf springs 16 (Figure 9). For convenience, a handle 18 is provided on the outer front surface of the unit 48 to facilitate its movement into and out of position. When the unit 40 is moved into its operable position, shown in Figure 9, electric circuit connections are automatically made through the cooperating male and female plug arrangements 82, 8|, such coop erating plugs serve to conduct current to the solenoids associated with the deflector plates ilJBB, 600C, and 46DD. In such operable position, the spring '56 is resiliently pressed against the bottom surface of the stationary shelf member 84 which is arranged to support the units 25, 26, 27 and 2B, and which is provided With apertures 85 to allow dates to pass therethrough.

The units 25, 26, 22', and 28 are likewise plug-in units, normally supported on the shelf member 84, and are each provided with a handle 88 to facilitate handling. The unit 25 itself comprises essentially two substructures, first, the substructure shown in detail particularly in Figures 13,

l4, and 15, and the cooperating substructure 89 iFigure 9.), comp-rising the so-called R. F. cells 593, :890, and 89D, into which respectively the banana-type terminals, shown in Figure 13 and associated with the condenser structures 25B. 25C. and :tD, are adapted to be plugged in respectively. The particular circuit element within one of the R. F. cells 83B, 89C, and 89D is shown in schematic form in the blocked. rectangles in Figure 30. Thus, these R. cells 8913,8530, and SEED are quickly attachably and detachably connected to the terminals of the electrode structures 26B, 26C, and 2 5D which are mounted as a unit with its handle member 86. The unit 125, azwhole, may be moved with its handles 98 and 8% (Figure 8). When the unit 25 is moved to the left, in Figure 9, as for example, by pulling on the handles 96 and 5H, the condenser structure 25B. 25C, and 25D and also the R. F. cells 89B, 39C, and 89D move to the left as a unit, the R. F cells 89B, 39C, and 85D being mounted on the casing of the unit 25 and being quickly attachable and detach- "able to the high frequency voltage terminal 9% through plug 65. The high frequency conductor 95. interconnecting the R. F. .cells 89B, 33C, and 89D, is a rigid member, is as short as possible, and is electrostatically shielded from the circuit elements in the R. F. cells and from the associated condenser structures.

Preferably, as described hereinabove, the electrode structures 26B, 26C, and 26D are detachable as a unit from the composite unit 26 to allow, for example, cleaning of the condenser structures and to effect removal of a date if, for example, one should stick in the condenser. Also. to eifect other circuit connections to the circuit components in the R. F. cells 89B, 89C, and 8913, there is provided a pair of cooperating plug and socket elements 98, 99 for each one of the units 25, 26, 21, and 28 so that all necessary circuit connections are automatically made when the units 25, 26, 21, and 28 are placed in proper supporting position on the shelf member 84. The high frequency voltage connections to the R. F. cells in each one of the units 25, 26, 27, and 28 are somewhat critical and are accomplished by the circuit'arrangements, illustrated in Figures 6 and 35 wherein the corresponding terminals have identical reference numerals. Such high frequency voltage is generated electrically and amplifiedin an R. F. amplifier whose ungrounded output terminal is represented at I60. This terminal IDS is connected to the midpoint of a structure IOI whose ends are connected to the midpoints I02, I03 respectively, of the conductors IM and I05. Opposite ends of lead I04 are connected respectively to terminals 94A, 94. Opposite terminals of conductor I05 are connected to terminals 94B and 94C. The terminals 84A, 94, 94B, and 94C are shown in Figures 6 and .8 and comprise the terminal to which corresponding R. F. cells in the various units 25, 26, 21, and 28 are releasably connected. Preferably, the leads Il, I04, and I (15 are as short as possible, of equal length and symmetrically disposed, as shown in Figures 6 and 35. These leads IIlI, I54, I are preferably shielded from the electrical elements in the units 25, 26, 27, and 28 as, for example, by the metal back plate IIi] upon which the various connectors are mounted.

The electrode structure associated with each one of the units 25, 26, 21, and 2B is shown in detail in Figures 9, 10, 11, 12, 13, 14, and 15, and is described immediately below.

The three electrode or condenser structures 8 26B, 26C, 26D each comprise eight .resilient'fingers I I I, disposed as shown .in Figure 14. Three ofrsuch fingers are interconnected by a metal bonding strip [12 to .form one plate of the condenser while three other fingers III are bonded together by a metallic connecter I I3 to form the other plate" of the condenser. The other two fingers of the eight fingers are diametrically dis posed on the central insulating supporting tube I30 and are connected thereto at their upper ends by fasteners I2I. These two diametrically disposed fingers remain dead and are not connected to other circuit elements. One plate of such condensers 26B, 26C, and 26D, thus formed by the use of the metallic connector I I2, are connected respectively to the terminals II5, H6, and II"I which, in :use, are at ground potential. The other plates of the condensers 26B, 26C, and 26D, formed by theme of the connector 'I It, are connected respectively to the terminals I23, IZI, and I22. The electrical shielding plates I24 and I25 are likewise connected "to the grounded terminals H5 and I I 6 respectively. The relative disposition of the bonding connectors II2 and H3 is of importance, and as shown in Figure 13, such connectors are staggered in the various condenser sections 26B, 26C and 26D to assure the taking of measurements on a single date in differently oriented directions, it being noted that a date may occupy,'at one particular time, only one of the condenser structures 26B, 26C, or 25D, and that in passing successively through these condenser structures, the date moves in its longi tudinal direction with substantially no rotation about such longitudinal axis.

Preferably, the bonding strips I I2, I 53, in each individual condenser 26B, 26C, or 26D, are so arranged that eifective measurements are taken through the date in three directions spaced apart.

In greater detail, as shown in Figures 14 and 15, the resilient spring electrode members I I I are hooked at their upper ends and pass through suitable apertures in the insulating tube I36 for support thereon while the bottom ends of such resilient fingers III extend gradually inwardly and are bent to form guide members with the apertures I30A in the tube I3fl through which they pass. The two fingers III not used in the condenser structure are fastened at their upper ends to the tube I33 while the remaining fingers are secured one-half to the bonding strip I I 2 and the other half to the bonding. strip I l3 by soldering, welding, and the like, such bonding strips I I2, II3 being maintained stationary on the tube I30 by, for example, rivets. It is noted that the bottom end of each one of such fingers is free to move radially with respect to the enclosing tube I33and that their bent ends provide a guide member, and also their upturned ends serve as stop members incorporated with the outer surface of the tube I30 against which they are resiliently pressed due to the inherent resiliency of. such fingers. As a date passes through, for example, electrode structure 263, the bottom ends of the fingers are pressed outwardly by the action of gravity forces on the date to assure a uniform and predetermined electrical contact with the date. In order to assure central movement of the date through the tube I36, there is preferably provided the spaced guide members I'3I, I32, I33, I34, I36, I36, and 31, each of insulated material and afiixed Within the tube I38. These insulating guide members I32, ESQ, and I 36 serve also as stop members for extended 9 movement of the fingers III to redistribute stresses on the various fingers in the event that a date tends to move through the electrode structures non-centrally with respect to the axis of the tube I30.

Figure 29 shows in schematic form a circuit arrangement embodying features of the present invention and utilizing the apparatus described/ The circuit shown in Figure 29 does not include an averaging arrangement as does the circuit shown in Figure 30, and only one of the electrode or condenser structures 263 in the three electrode arrangements shown in Figure 9 is utilized in making measurements or determinations. The principle of operation of the circuit shown in Figure 29 is embodied in the simplified circuit arrangement shown in Figure 28.

In Figure 28, the electrode or condenser structure 2613, between which dates are successively passed, one of its terminals grounded'and the other one of its terminals connected through condenser 20 to the anode of the measuring rectifier device I2I having its cathode grounded. Also, the terminals of the condenser structure 233 are connected in parallel to the tuned circuit comprising the inductance I22 and variable condenser I23.

An RF voltage from source I24 is applied across the terminals of the condenser 25B, the magnitude oi the voltage across such condenser being adjustable by the adjustable serially connected condenser 5523 having the resistance I21 con nected in parallel therewith. serially connected resistances I23 and I29 are connected between the anode and cathode of the device I2I and thus resistance I serves as a load circuit for he rectified output of the measuring diode rectifier I2I. The resistance I28 and condenser I30, connected across opposite terminals of resistance :29, serve as a filter network to produce a filtered rectified voltage output across the terminals of resistance I29 in accordance with the dryness or wetness of the date in the electrode structure B. The greater the degree of wetness or moisture content in the date, the less positive becomes the lead, I32, which is connected to the junction point of resistance I28 and I29 and is also connected to the cathode of the thyratron tube I33. The tube I33 is always in condition for firing because of the I unidirectional voltage source I34, serially connected with the relay winding across the oathode and anode of the device I33.

The control grid I31 of the thyratron tube is connected to an adjustable tap on the potentiometer resistance I36 which has a reference voltage applied across its outside terminals. Such reference voltage is proportional to the magnitude of the voltage from the RF source I24 and is unidirectional in character. Such unidirectional voltage is produced by connecting the ungrounded terminal of source I24 through condenser I38 to the cathode I39 of the reference diode rectifier I40, the anode of the diode- I40 being grounded.

Resistances I42 and I are serially connected across the terminals of the diode and the resistance I42 together with the condenser I43, connected in parallel with the resistance I36, serve as filter elements.

The voltage thus applied to the control grid I3? is substantially constant but varies with changes in magnitude of the RF voltage from source I24, and in operation of the device, the potential of the cathode of device- I33 is altered 10 with respect to the potential of the grid I31 to fire the thyratron tube I33.

An important feature of the arrangement described in Figure 28 is that the net voltage be tween the cathode and control grid of the device I3-3 is substantially independent of the mag nitude of the R. F. voltage. The operation of the thyratron tube I33 is thus substantially independent of variations of the voltage of the R. F. source, and once it is fired, the current fiow thereinthrough produced by the source I34, causes the relay winding I35 to be energized the associated relay switches to be actuated to eiiect a control operation as described in greater detail hereinafter.

The circuit shown in Figure 23 is a simplified version of the circuit used, shown in Figure 29, wherein corresponding parts have identical references. It is noted that, in comparing Figures 28 and 29, a cathode follower circuit I89 is interposed in Figure 29, on the one hand, between lead I32 and the cathode of thyratron device I33, and, on the other hand, a cathode follower circuit I90 is interposed between the control grid 13? of device I33 and the variable tap on potentiometer resistance I9I through serially connected resistance ISI and switch I353.

The anodes of the cathode follower stages I89 and 90 are connected to the positive terminal of voltage source I 92, and their control grids I93 and I04 connect respectively to lead I32 and I98. The cathode of the reference cathode follower stage I90 is connected to one terminal of the voltage dividing circuit I9I through the adjust-able resistance I99, and the cathode of stage IE0 is connected to the other terminal of the voltage dividing circuit I9I through the serially connected resistances 200 and 20I whose junction point is connected to the junction point of resistances I29 and I38. The voltage dividing network I0! comprises the three potentiometers 202, 203 and 205, the potentiometer resistances 202 and 234 being serially connected to form a serial circuit, and the third potentiometer resistance 203 being connected in parallel with the aforementioned serial circuit.

The variable taps on these resistances 202, 203, 204 are connected respectively to a normally closed contact on the relay switches I35A, I45A, ISDA of the associated relays having respectively the actuating windings I35, I45 and I50. The other switches operated when relay windings I35, I45 and I50 are energized are respectively the switches I353, M53 and I50B. All of the relay switches are each of the single pole, double throw type.

The movable contacts of switches I35A, I 45A and I50A are each respectively connected to the control electrodes of the corresponding thyratron tubes I33, I41, I51 through corresponding decoupling resistances I5I, NH and I'll.

The control electrodes of tubes I33, I41 and I51 likewise are connected to the lead 205 through the corresponding resistances I54, I64 and I14.

The cathodes of each one of the devices I 33, I41, I51 are interconnected and connected through lead 206 to the cathode of the measuring cathode follower I89. The potential of this lead 206 is varied in accordance with the moisture content of the date to fire the thyratron tubes I33, I41, I51. The screen grids of these tubes I33, I41, I51 may be connected to the lead 206 through corresponding resistances I10, I86, I96, and corresponding condensers I15, I85, I95 are connected between the control grid and cathode of the thyratron devices. The anodes of devices I33, I41, I51 are each connected to their associated cathodes through a serial circuit comprising a condenser and resistance, respectively condenser I52, resistance I53; and condenser I52, resistance I63; and condenser I12 and resistance I13. These anodes are connected respectively to the cathodes of devices I48, I58 and I88 whose associated anodes are connected in a manner described presently to the upper terminal 208 of the secondary winding of the transformer I88 energized with alternating current.

This terminal 208 is connected to the anode of device I58 directly through the relay winding I55, while the other two anodes of devices I58 and I48 are connected to the same terminal 208 through their associated relay windings I45 and I35; but, it is noted that the relay winding 145 is connected to terminal 208 through the normally closed elements of switch I503 while, in similar manner, the relay winding I35 is connected to the same terminal 208 through the serially connected portions of the normally closed switches I453 and I50B. Also, the terminal 208 is connected to the anode of device I83 through the serially connected normally closed portions of switches I353, I45B and I50B, to provide a positive control voltage useful for a purpose described hereinafter, it being noted that the other terminal of the secondary winding of transformer I88 is connected to lead 206 which, in turn, is connected to the cathode of device I83 through a condenser I18 to thereby normally produce a unidirectional voltage across condenser I18 with the polarity as indicated.

Also, the cathode of the rectifier device I83 is connected to the junction point of resistances I11 and I19. The resistance I19 has one of its terminals connected to the cathode of device I83 and its other terminal connected to the junction of the resistances I82 and I14 and to lead 205. The other resistance I11 is connected between the cathode of device I83 and the normally open contact of each one of the switches 135A, I45A and I50A.

The rectifier device I84, arranged to normally provide a negative control voltage of approximately 150 volts, has its cathode connected to the terminal 208 of the secondary winding and its anode connected to the lead 205 through the resistance I82; It is noted that the condenser I80 is connected between the lead 208 and to the anode of device I84 through resistance I82 so that it is charged so as to normally maintain the lead 205 negative. Also, the anode of device I84 is connected to the lead 206 through the condenser I8I. The condensers I80 and ISI and resistance I82 serve as filter elements for the negative voltage produced by device !84 and applied to lead 205.

Thus, the condenser I18 is normally charged to make the lead 209 positive with respect to lead 206. However, when either one of the relay windings I35, I45 or I55 is energized, this condenser I18 is allowed to discharge and in discharging, the condenser I18 discharges through two paths, i. e., a first path includes the path through resistance I19 toward minus 100 volts established by the potential of lead 205, and through a second path which includes the resistance I11 and through the normally open contact of the particular relay switch I35A, I45A, I50A, as the case may be, depending upon which switch is actuated to thereby apply transient voltage to the grid oi the corresponding tubes I33, I41, I51 through 7 5151291 1 R9PWQ1L 1 .9 rende such grid progressively from a high positive voltage of volts to a voltage which is negative, and after a short time delay, depending upon the time constant of the two condenser discharge paths, to cause the initially fired tube I33, I41, I51, as the case may be, to cease firing when their corresponding anodes, now supplied with alternating current, become negative also.

The apparatus in Figure 29 is so adjusted that a very dry date passes therethrough without firing any one of the tube I33, I41 or I51. The tube I33 is fired when the date has a relatively small moisture content above a predetermined moisture content; the tube I41 is fired when the date has a medium moisture content; and the tube I51 is fired when the date has a relatively large moisture content. It will be noted here that in the event that the date has a relatively large moisture content, each one of the tubes I 33, I41, and I51 is initially fired but only the solenoid winding 6ID, associated with the device I51, is energized. Likewise, when the date ha a medium moisture content, tubes I33 and I41 are fired but only the solenoid winding 6IC associated with the tube I41 is energized. Likewise, when the date has a relatively small moisture content, above such predetermined low moisture content, the tube I33 is fired and the associated winding BIB is energized. These solenoid windings 6IB, 6IC and BID are associated respectively with the solenoids arranged to operate the date deflecting gates 40BB, 40CC, and 40DD, previously described in connection with Figure 16.

The solenoid windings 6 B, SIC, 6ID, associated with tubes I33, I41 and I51, are connected in parallel respectively with the associated relay windings I35, I45, and I55, each of which has a corresponding shunt connected condenser I49, I59, I69, these solenoid windings preferably having a corresponding serially connected resistor I50, I60, I10. These solenoid windings are so interconnected with respect to the terminal 208 through the switches I35B, 245B that a priority arrangement is provided in that when tubes E33 and I41 are fired, the switch I45B is actuated to disconnect the solenoid 6 IB from the terminal 208 of the secondary winding, in which case even though the relay windings I35 and I45 are initially energized, only the solenoid winding 0IC is energized. Likewise, when a relatively large voltage is delivered from the voltage divider I9I to fire each one of the tubes I33, I41 and I51, each one of the relay windings I35, I45 and I55 are energized but only the solenoid winding BID is energized, it being noted that when the relay winding I55 is energized, the switch I50B is actuated to thereby disconnect the solenoid windings BIC and BIB from the terminal 208 of the secondary winding.

In operation of the arrangement shown in Figure 29, assuming that a date passes through the electrodes with relatively small moisture content below a predetermined moisture content, the date will not affect operation of the apparatus shown in Figure 29, and such date will pass direct y through the electrodes and central tube 40A (Figure 9) without firing any thyratron tubes. Assuming, however, that the date has a moisture content slightly greater than the predetermined low moisture content, a voltage of sufiicient intensity is delivered from the tap on resistance 202 through the normally closed contacts of switch I35A and through. the decoupling resistance I5I to the grid I31 of device I33. Stated in other a s, the ent l of the e h d ead 236 is changed to make the grid of device I33 positive with respect to its cathode to initiate firing of the tube I33. As soon as tube I33 is fired, the condenser i52, previously charged with current flowing from the terminal 208 and through switch I50B, I45B, relay winding I35 and tube I48, discharges through the tube I33 to maintain the tube I33 ionized when and as the movable switch elements of the associated relay moves to its other positions wherein its normally open contacts are engaged. This discharge of condenser I52 is suitably prolonged for this purpose by the presence of the serially connected resistance I53. After the relay switch elements are. thus moved to engagement with the normally open contacts, it is noted that the grid I3? is then connected through the resistance I5I and resistance IT! to the lead 209 of positive decaying potential; and, also, at the same time, the movable switch element of switch I35B engages its normally open contact member to produce an indication on the lamp 81, and simultaneously to interrupta chargin current path for condenser Il8 in which case the condenser I73 discharges through two paths, mentioned previously, toward a potential of minus 100 volts established on lead 285 by rectifier I84. As the condenser I13 is thusgdischarged through the two aforementionedpaths, the voltage of grid I37 gradually becomes negative with respect to its cathode, and since the anode of the device I 33 is now supplied with alternating current, the tube will cease firing orbecome substantially non-conductive again. In order to prevent refiring of the tube when the alternating current wave on the anode of tube I33 assumes a positive value, the con denser I75 with the shunt connected resistance I54 are provided having, at this time, a negative charge thereon to prevent refiring of the tube.

Similarly, when the datehaving medium moisture content is passed through the electrode system, a sufficient voltage is produced to fire the tubes I33 and I41, but, as mentioned hereinabove, the switch I 4513 is so connected as to give the circuit associated with the tube 54'! priority over I the circuit associated with the tube I31, this being accomplished, as mentioned hereinabove, by disconnecting the relay winding I35 from the terminal 203; The operation of the circuitassoelated with the tube I4! is identical with the operation of the circuit described in connection with the operation of the tube I33. Similarly, the operation of the circuit associated with the thyratron tube i5! is identical with the operation of the circuit associated with the tubes I33 and I41, it being noted that when a sufficient voltage is developed in the voltage divider circuit I9! to initially fire the tubes I33, I47 and I57, only the circuit associated with tube I5! is afiected.

Figures 30 and 31 show another circuit arrangement which is preferred in actuating the mechanism of the structure described previously in connection with the description of Figures 1-27 inclusive. Corresponding parts in Figures 30 and 31 have identical reference numerals and Figure 31 is presented to more clearly present certain principles of operation of the circuit shown in Figure 30.

A characterizing feature of the circuit shown in Figure 30 is that the solenoid windings SIB, SIC, BID are actuated in accordance with sub- 'stantially the average of three readings taken in diiferently oriented directions by use of the three electrode condenser structures 26B, 26C. 26D shown in Figures 13 and 30.

Another characterizing feature of the apparatus shown in Figure 30 is that it allows the use of four date channels each fed from a single high-frequency voltage source, as shown in Figures 6 and 35, each channel being effective, as the channel shown in Figure 30,. to actuate one of a plurality of gate solenoids in accordance with the average of three different readings taken on the same date.

The apparatus in Figure 30 is adjusted to allow a date of low moisture content below a predetermined magnitude to pass through the apparatus without firing any of the thyratrons. The thyratron tube 229 effects operation of the corresponding date solenoid SIB when a date of slightly greater moisture content than said predetermined moisture content passes through the apparatus. The thyratron tube 230 effects operation of its associated solenoid SIC to separate dates having a medium moisture content, and the third thyratron tube 263 effects operation of its date solenoid SID to separate dates with relatively high moisture content, i. e., wet dates. A priority arrangement is also incorporated in the circuit shown in Figure 3G, in that, when, for example, a date of relatively high moisture content passes through the apparatus, each one of the thyratron tubes 223, 23%, 2 30 is fired but only the date solenoid associated with solenoid winding SID is actuated.

Similarly, when dates of medium moisture content pass through the apparatus, the thyratron tubes 223 and are each fired but. only the gate solenoid associated with solenoid winding SIC is actuated. When dates pass through the apparatus having a moisture content slightly greater than said predetermined low magnitude, only the thyratron tube 225 is fired and. its date solenoid associated with winding 61B is actuated.

These three tubes 226, 231! and 240 are each fired in a manner similar to that described in connection with Figure 29, but the magnitude of voltage applied between the control grid and cathode of these individual tubes is in accordance with the average value of three different voltage readings obtained when a date passes successively through the electrode structures 26B, 26C and 26D.

In general, such average voltage for effecting operation of the thyratron tubes is obtained by charging the condensers 22IB, 22IC and 22ID in accordance, respectively, with the moisture content determinations obtained when a date is in electrodes or condensers 26B, 26C and 26D, and thereafter connecting such charged condensers together through the normally open relay switches 222B, 222C and 2221). The average value of voltage thus obtained appears across the voltage dividing network 223 from where selected predetermined portions thereof are applied to the cathode-co-.trol grid circuit of tubes 220, 230, 243. For purposes of simplicity, the averaging circuit is omitted in Figure 31 to more readily make apparent the manner in which the voltage differential between the control grid and cathode of the thyratron tubes 22D, 23D and 240 are varied to control their firing.

The circuit shown in Figure 31 includes a diode rectifier 224 to develop a reference voltage in accordance with voltage variations of the RF source I 24, a reference cathode follower stage 225 to produce increased current variations, a measuring or electrode diode rectifier 226B to develop 

